def tag(name,*content,cls = None ,**attrs):
	'''生成一个或多个HTML标签'''
	if cls is not None:
		attrs['class'] = cls
	if attrs:
		attr_str = ''.join(' %s ="%s"' % (attr,value) for attr, value in sorted(attrs.items()))
	else:
		attr_str = ''
	if content:
		return '\n'.join('<%s%s>%s</%s>' % (name, attr_str ,c ,name) for c in content)
	else:
		return '<%s%s />' % (name, attr_str)

print(tag('br'))
print(tag('p','hello','world'))
print(tag('p','hello','world',cls = 'sidebar'))
print(tag(content='testing',name='img'))